The present invention relates to digital cameras comprising a disk drive device which is adapted to record on a disk images photographed by an image pickup device such as a CCD (charge-coupled device) and image management data as to the images as digital data, or to reproduce the images and image management data recorded on the disk.
Digital cameras are known in recent years which are equipped with a disk drive device capable of recording the images photographed by an image pickup device, such as a CCD, on an erasable optical disk, hard disk or like disk as digital data, or reproducing the images recorded on the disk.
Optical disks have a region for recording the images photographed by a CCD, and a region for recording image management data as shown in a signal recording format of FIG. 4. When the digital camera equipped with a disk drive device, for example, for optical disks is used for taking photographs, image data as to the image photographed by the CCD is converted to digital data and then compressed according to the JPEG (Joint Photographic Coding Experts Group) system or MPEG (Moving Picture Coding Experts Group) system, and the compressed image data obtained is recorded as an image file in the image recording region of the optical disk. Image management data as to the image file is recorded in the image management data recording region. The image management data contains, for example, a file name indicating the name of the image file, and position data indicating the position where the image file is recorded.
With the digital camera of the type described, the image management data recorded on the optical disk is read therefrom and written to a RAM or like memory incorporated in the camera main body when the user turns on the power source of the camera main body with the disk set in the disk drive device, or when the user sets the disk in the drive device with the power source turned on.
When the user thereafter performs a predetermined procedure for reproducing the desired image file among a plurality of image files recorded on the disk, the image file selected by the user is specified with reference to the image management data written to the memory as described above and reproduced from the disk.
Since the memory used in the conventional digital camera described is a volatile memory, the image management data stored in the memory disappears immediately when the power source of the camera main body is switched off to discontinue the supply of power to the memory.
Accordingly, even in the case where the power source of the camera main body which is on is switched off with the disk set in the drive device, and the power supply is thereafter turned on without changing the disk, it is necessary to move the pickup of the drive device to the image management data recording region of the disk to read the image management data again from the disk and write the read data to the memory.
Thus, there is a need to read and write the image management data every time the power source of the cameral main body is turned on whether the disk is replaced or not, so that the conventional digital camera has the problem of necessitating great power consumption.
An object of the present invention is to provide a digital camera which is reduced in power consumption.
The present invention provides a digital camera comprising an image pickup device and a disk drive device adapted to record on a disk images photographed by the image pickup device and image management data as to the images as digital data, or to reproduce images and image management data recorded on the disk. The digital camera is characterized in that the camera comprises:
memory means comprising a nonvolatile memory for storing the image management data recorded on the disk,
information processing means for reading the image management data from the disk as placed in the disk drive device and writing the read image management data to the memory means when a power source of main body of the camera is turned on,
means for storing therein a flag having a first value indicating a need to cause the information processing means to read and write the image management data or a second value indicating that there is no need to do so,
flag processing means for rewriting the flag in response to an action of a user, and
power supply means for holding the flag storing means and the flag processing means in operation at all times. The information processing means comprises:
means for checking whether the flag stored in the flag storing means has the first value or the second value when the camera body power source is turned on, and
data processing means for reading the image management data from the disk as placed in the disk drive device and writing the read image management data to the memory means when the flag has the first value.
With the digital camera of the present invention, the image pickup device, disk drive device, memory means and the information processing means are in operation with power supplied thereto while the power source of the camera main body is on, and are held out of operation with the power supplied discontinued when the power source is off.
On the other hand, the flag processing means is held in operation at all times, always detecting the action or manipulation by the user, if any, whether the camera main body power source is on or off. The flag processing means rewrites the flag in the flag storing means, for example, when the disk is drawn out of the drive device by the user or when the user turns on the power source for the data processing means to write image management data to the memory means as will be described below. Since the flag storing means is held in operation at all times, it is unlikely that the flag in the flag storing means will be lost by turning on the power source of the camera main body.
With the digital camera described above, a plurality of images photographed by the image pickup device are recorded on the image recording region of the disk, and image management data as to these images is stored in the image management data recording region thereof.
Immediately when the user sets in the drive device the disk having the images and image management data recorded thereon as described above and turns on the power source of the camera main body, power is supplied to the image pickup device, disk drive device, memory means and information processing means. The checking means of the information processing means checks whether the flag in the flag storing means has the first value or second value.
When the flag is found to be of the first value by the checking means, the image management data is read from the region recording this data on the disk, and the read image management data is written to the memory means. The camera is then made ready for photographing and image reproduction.
If the flag is found to be of the second value by the checking means, on the other hand, the camera is made ready for photographing and reproduction without the reading and writing of the image management data. Since the memory means comprises a nonvolatile memory, the memory means has stored therein the image management data immediately before the camera main body power source is switched from off-state to on-state previously, and the image management data in the memory means is in match with the image management data recorded on the disk as set in the drive device.
With the digital camera of the present invention, the image management data is read and written when the camera main body power source in off state is turned on only in the case where the flag has the first value, so that the camera is smaller in power consumption than the conventional digital camera wherein the image management data is read and written every time the camera main body power source is turn on.
Stated more specifically, the flag processing means comprises:
means for detecting withdrawal of the disk from the disk drive device, and
flag rewrite means for changing the flag value to the second value in response to a flag rewrite command and changing the flag value to the first value when the disk is drawn out of the disk drive device; and the information processing means comprises:
means for commanding the flag rewrite means to rewrite the flag when the image management data has been read and written by the data processing means.
When the camera main body power source which is off is turned on by the user, with the disk set in the drive device, the flag is checked as to whether the flag has the first value or second value as stated above, and the image management data is read and written in the case where the flag is of the first value. At this time, a flag rewrite command is given to the flag rewrite means to change the flag from the first value to the second value.
The user will turn on the camera main body power source after turning off the power source with the disk set in the drive device, drawing out the currently set disk from the drive device for replacement and setting another disk in the drive device. At this time, the flag is checked for the value. The flag is found to be of the first value if the disk is drawn out while the power source is off. The image management data is therefore read and written, and the camera then becomes ready for photographing and reproduction.
On the other hand, the user will turn off the camera main body power source with the disk set in the drive device and thereafter turn on the power source without replacing the disk. At this time, the flag is checked for the value. The flag is then changed from the first value to the second value as stated above and is thereafter held at the second value. Accordingly, the camera becomes ready for photographing and reproduction without the reading and writing of the image management data.
With the digital camera having the foregoing construction, the image management data is read and written to a memory upon the power source of the camera main body being turned on only in the case where the disk has been replaced with the power source off.
Further stated more specifically, the information processing means comprises first updating means for updating the image management data on the disk in response to an action of the user, and second updating means for updating the image management data written to the memory means upon updating of the image management data on the disk.
For example when the digital camera thus constructed is used for photographing, the image photographed by the image pickup device is recorded on the image recording region of the disk, and the image management data in the region for recording this data is updated. The image management data stored in the memory means is also updated.
Accordingly even in the case where the user turns off the power source of the camera main body after photographing an image and subsequently turns on the power source again without replacing the disk, the image management data stored in the memory means is in match with the image management data recorded on the disk, so that the image management data need not be read or written when the power source is turned on. This results in a further reduction in power consumption.
With the digital camera of the present invention, the image management data is read and written when the power source of the camera main body is turned on only in the case where the flag has the first value. The camera is therefore smaller in power consumption than the conventional digital camera wherein the image management data is read and written every time the power source of the camera main body is turned on.